Solar arrays for use on spacecraft are known. In particular, such solar arrays are used for powering spacecraft based on photovoltaic (PV) conversion of solar radiation. Various solar cell arrangements for converting solar radiation into electricity have been proposed for space applications.
In general, photovoltaic concentrator arrangements may be used to increase the energy output per unit area occupied by the photovoltaic cells. Such a concentrator arrangement is generally designed to receive solar radiation in an effective collection area and to redirect this received radiation towards the photovoltaic cells. As a result, the photovoltaic cells only need to occupy a part of the solar array.
In space applications, the requirements for solar cell quality (e.g. efficiency, robustness, etc.) are typically very high. The cost of the photovoltaic assembly may be about 50%-60% of the total solar array cost, and about 5%-7% of the total system spacecraft cost. A reduction of the required number of solar cells will therefore contribute significantly to an overall system cost reduction. Compact efficient solar cell arrays and concentrator arrangements are therefore preferred in space applications.
Patent document U.S. Pat. No. 5,344,496 (STERN et al.) describes a solar concentrator cell array for use in space applications, including an arrangement of longitudinally extending mirror elements with parabolic cylindrical surfaces, each of which focuses received sunlight onto a photovoltaic element that is located on a backside of an adjacent mirror element. The described mirror elements are incorporated in a rigid box-like structure that is self-supporting.
Depending on the power requirements of the spacecraft, several solar panels may need to be connected in order to obtain a sufficiently powerful solar array. Typically, such panels are mechanically connected in a foldable manner, so as to be folded-up in a stowed state prior to launch, and to be able to unfold into a deployed state after the launched spacecraft has assumed its intended trajectory in space (e.g. a planetary orbit). U.S. Pat. No. 5,344,496, however, does not disclose methods for coupling multiple solar panels, nor does it disclose mechanisms for stowing or deploying the described concentrator cell array.
It would be desirable to provide a solar array for space applications which not only provides a high energy output per unit of PV cell occupation area, but which also complies with various geometrical and mechanical requirements for the stowed state as well as the deployed state of the spacecraft.